-- Just for fun, playing with the old Zip Reduce format...
--
-- Reduce combines LZ77 with a probabilistic using a Markov chain.
-- The format has a single block for the whole file :-(.
--
-- NB: this compressor works in two passes, the first one
-- serving to compute the exact Markov matrix for the whole
-- data to be compressed. Hence, it is slow. However,
-- we cache the last n=LZ_cache_size bytes compressed by LZ77.
-- The result is optimal - within the constraints of that format:
-- one block, poor encoding of compressed data and of the
-- compression structure (the Markov matrix).
--
-- Author: G. de Montmollin, January 2009
--
private procedure Zip.Compress.Reduce(
input,
output : Zip_Streams.Zipstream_Class;
input_size_known: Boolean;
input_size : File_size_type; -- ignored if unknown
feedback : Feedback_proc;
reduction_factor: Positive;
CRC : in out Interfaces.Unsigned_32; -- only updated here
output_size : out File_size_type;
compression_ok : out Boolean -- indicates compressed <= uncompressed
);